Valve lifters in some internal combustion engines, especially high-speed automotive engines, use rollers that ride in contact with the cams of cam shafts that operate the lifters. As the cam shaft rotates the cams reciprocate the lifters which are cylindrical and move in cylindrical bores of the engine block. It is necessary to prevent the valve lifters from rotating in the bores in order to keep the rollers properly aligned with the cams. Lifters are typically aligned in a row along the cam shaft with a cam being provided for each of the lifters.
Various means have been suggested to prevent rotation of the valve lifters. U.S. Pat. Nos. 5,022,356 and 4,173,954, for example, utilize bridging members which interconnect adjacent lifters so that the lifters can not rotate and thus the rollers would be maintained in their proper position for contact by the cams.
An object of this invention is to provide an arrangement for preventing rotation of valve lifters which does not require any interconnection between adjacent lifters.
A further object of this invention is to provide such an arrangement or mechanism that is effective in operation.
A still further object of this invention is to provide such an arrangement or mechanism wherein each valve lifter would have its own structure independent of other valve lifters for preventing rotation.
In accordance with this invention each cam lobe on the cam shaft would be provided with a confinement member located on one side of the cam lobe. The valve lifter would have an abutment member located at its roller follower in such a position to be disposed against and in contact with the confinement member. Thus, as the cam lobe rotates the confinement member rotates with the cam lobe but maintains surface to surface contact with the abutment member. This surface to surface contact prevents rotation of the valve lifter.
In a preferred practice of this invention a confinement member is provided on each side of each cam lobe and a corresponding abutment member is disposed on each side of the roller follower of the cam lifter. The confinement member is of non-circular cross-section and preferably has an outer surface that complements the outer surface of the contacting portion of the abutment member to maintain surface to surface contact without any significant degree of rotation. These contacting surfaces or edges may be tapered or beveled surfaces. Each confinement member may also have a second beveled edge in surface to surface contact with a beveled edge of the roller.